Antistatic properties of clearcoats by the use of special additives

Abstract

Electrostatic discharge and dust attraction are everyday life phenomenon, which are undesirable in most cases. In coatings, antistatic additives can solve this issue by reducing the surface resistance of surfaces. By way of formulation, antistatic coatings might prevent electrostatic discharge and dust attraction. In this work, we evaluated different substances to investigate and understand their ability to create an antistatic effect, specifically in a UV clearcoat. We have developed a method to evaluate the suitability of antistatic additives by investigating their location within the coating matrix by FTIR, versus the location of the coating resistance and resultant coating performance. We compared an array of different chemistries used to impart antistatic effects, from classic quaternary salts to polymeric materials and pigments, to better understand how they perform in a coating and to understand any benefits or issues. All additives helped to reduce surface resistance and therefore improve the potential for antistatic performance. We found the most powerful effects on reduced resistance from the ionic liquid and conducting pigment, but they were unable to target the surface where the effect was needed for an antistatic behavior. Additives at the surface gave the strongest effect, but they mostly relied upon increasing hydrophilicity and as a result reduced coating hardness and tended to leach from the coating. Modifying the quats (quaternary ammonium cationic materials) with PDMS (polydimethylsiloxane) gave the strongest surface affinity, but we believe this diluted the effect of antistatic behavior versus lower molecular analogues due to the lower molar concentration of active groups. We believe our work could be used by formulators to better design additives that find the correct location within a coating to avoid waste and side effects, and to address the issue of permanence through crosslinkable modification.